How To Add Daytime Running Lights

Most cars sold after the late '80's are equipped with daytime running lights. This means that the low beam headlights are kept on all the time. This makes your car much more visible to oncoming traffic and thus reduces the risk of a head on collision.

Obviously, for most cars with flip up headlights, this system won't work. There is no way to light the headlights without putting them up. However, the RX-7 has those useless flash to pass lenses. In Japan, these lenses contain another light which functions as a daytime running light. Such Japan spec lights are available from Rotary Performance for around $165 each. This price is a little excessive, considering that you can add this feature for under $10. The key is that on the RX-7, the headlights can be lit without lifting them, and will shine through the previously useless flash to pass lenses. This modification will probably take no more then 1 hour.

Instructions

Step 1 - Remove the instrument bezel

First remove the plastic cover around the steering column by taking the four screws out of the bottom, snapping off the metal keyhole ring, and then separating the two halfs. The bottom should fall off, but the top may need to be wiggled to slide it out. Now the five screws on the bezel can be removed. The picture below shows their locations.

Pay attention when removing the bottom screws. You want to take out the large ones, not the small ones. With all the screws out, you should be able to slide the bezel out about 2.5 inches. This should expose the back of the switches and the associated wiring harness.

Step 2 - Modify the wiring harness

Looking at the headlight switch wiring harness, locate the red wire with the white stripe. It will be on the right side of the plug, second from the top. Use a sharp knife to strip off about 1/4" of insulation about 1" from the plug. Solder on a length of wire. The gauge of the wire is unimportant, so use whatever you have around. Insulate the connecting using black tape, liquid tape or other suitable substance. Route the wire you soldered on down behind the dash following the stock harness. You may find it easier to perform the above step with the plug removed from the switch.

When grounded, this wire will turn on the headlights but will not raise them.

Step 3 - Connect your wire to ground

Connecting this wire directly to ground is not a good idea, as the lights will remain on all the time, even when the car is not running. So, it must be run through a switch. There are two methods of doing this:

Method 1: Connect the wire through a switch. The switch can be mounted in the dash or any other suitable connection. One end of the switch would be connected to your wire, the other end connected to ground. This will give you manual control over the lights.

Method 2: Connect the wire though a relay. The wire will be connected to ground, with a relay in series with that connection. The relay can then be activated by a +12V signal. That signal can come from the accessory line, or ignition line. This provides automatic control of the lights. One side of the relay coil is connected to ground, the other end is connected to your switches +12V source. If you would like to use the ignition or accessory wire, you will find the black wire with the white stripe on the steering column harness very convenient. This will light the lights when the car is running or the ignition key is in the "run" position. You can, of course, connect a switch in series with this connection to retain manual turn-off capability of the lights.
The schematic below should help you:

Step 4 - Reassemble

Now you can reassemble the parts you removed. Put the bezel back and tighten the screws. Don't over tighten or you will crack the plastic. Put the steering column cover back on by clipping the two halfs together then installing the screws in the bottom half. Now clip the key ring back on.

Step 5 - Test

Turn the key to the run position and/or flip your switch. If there is a burning smell or anything abnormal, immediately turn it off and troubleshoot your connections. It is normal for the CPU to beep, as the car is not running but the lights are on. Walk around to the front of the car and verify your lights are on.

Notes

1. Don't mess around with your headlight switch wiring unless you know exactly what you are doing. If you do, you will most likely fry your headlight switch, turn signal lever, or both.

2. If you use the accessory wire to activate your relay, your headlights will be on anytime the switch is in accessory position. You may want to include a switch to turn them off to avoid battery drain.